LTE (Long Term Evolution) is a long-term evolution of the UMTS (Universal Mobile Telecommunications System) technology standard developed by the 3GPP (3rd Generation Partnership Project).
In the LTE system, a base station needs to transmit a cell-specific reference signal periodically, and a UE (User Equipment) synchronizes with the base station in time and frequency by tracking the reference signal. In general, the cell-specific reference signal is also referred to as a common reference signal. In some cases, the UE may perform channel estimation by means of a UE-specific reference signal, to receive data.
In a 5G (5th Generation) system, in order to satisfy requirements of different application scenarios and deployment scenarios, different sub-bands may have different carrier numerologies, such as subcarrier spacing, CP (Cyclic Prefix) length and the like. Further, different sub-bands may have different waveform configurations, for example, the waveform may be multi-carrier, single carrier, etc., to meet requirements of different service data transmissions. Since the carrier numerologies of different sub-bands are not the same, existing common reference signals can not realize time and frequency synchronization between the UE and the base station.